Best base layers for women UK 2023: stay cosy and comfortable with thermal base layers for outdoor adventures
A thermal base layer is brilliant for keeping your temperature regulated as you adventure outside. Here are the best around
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Thermals, long johns, base layers – whatever you want to call them, there’s nothing like a warm layer worn next to the skin to help keep the chill of colder weather at bay.
Whether you’re off skiing, hiking or cold weather camping, layering up is the best way to trap in heat and keep cosy in the great outdoors – and a good layering system starts next to the skin with a quality base layer top and leggings set.
Thermals should hug your body without feeling too restrictive around the waistband, ankles, neck or sleeves.
Some base layers are stretchier than others – we reckoned thermals with some stretch offered more warmth on test, as there’s no empty space between the fabric and your skin for the cold to creep in.
Thermal tops usually have a crew neck or a high, zipped neck – the latter can double up as a neck warmer, and some tops also sport hoodies for extra warmth. We also look for base layers that use ‘flatlock’ sticking – this avoids any rubbing against your skin.
Best ladies’ thermals at a glance:
- Best 100% merino wool/best on test: Icebreaker Merino Oasis top and leggings
- Best for style points: Arc’teryx Motus AR long sleeve top
- Best for running: Runderwear long sleeve top
- Best winter bottoms: Jack Wolfskin Iseler Tights W
- Best on a budget: Alpkit Koulin Trail long sleeve top
- Best for comfort: Acai Winter top and bottoms
- Best for posture: CEP Wingtech short sleeve top
- Best for skiing: Haglofs Actives Wool top and bottoms
- Best for hiking: Paramo Grid Technic long sleeve top
What material should your thermals be made of?
Many base layers are made with synthetic materials such as polyester, but the best (but often the most expensive) base layers are made with a percentage of merino wool – merino is very warm but still highly breathable, and is great at wicking away sweat.
It also has naturally antimicrobial properties, making it perfect if you’re getting active or for when you’re heading into the backcountry without a shower in sight.
Bamboo base layers are more recent arrivals on the market – they’re also a great choice, as they’re soft to wear, antimicrobial and more eco-friendly to produce than synthetic materials.
What do the numbers on thermals mean?
You may see base layers listed with a number, such as 140 or 220 – this refers to their weight in grams, and the higher the number, the warmer, but heavier, the base layer.
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